1. Field of the Invention:
The present invention relates to an electroluminescence display panel in which light-emitting elements utilizing the electroluminescence of an organic material are arranged in a matrix, and a method for producing the same.
2. Description of the Related Art:
An electroluminescence display panel in which an organic material for obtaining electroluminescence and metal electrodes (serving as upper electrodes) for transferring a current are subsequently deposited by a vacuum vapor deposition method on a glass substrate with patterned ITO (indium tin oxide) transparent electrodes (serving as lower electrodes) is known.
In such a display, light is emitted from the portions of the organic material which are interposed between the ITO electrodes and the metal electrodes. In the case where the ITO electrodes and the metal electrodes are both patterned into a stripe shape, and arranged so as to intersect each other (e.g., orthogonal to each other), an electroluminescence display panel capable of providing a dot-matrix display can be obtained.
For fabricating such a display panel, the metal electrodes are patterned by depositing a metal material on the substrate through a metal mask having desired opening patterns. However, patterning the metal electrodes using a metal mask has the following problems.
In the case of the metal mask for forming stripe patterns for providing image display, the metal mask has a large open area and a small mask portion. Such a metal mask thus has a poor mechanical strength. Therefore, the metal mask is likely to be bent and partially separated from the substrate surface.
When the metal mask is partially separated from the substrate surface and a gap is produced therebetween, a material being deposited is introduced into the gap, thereby causing defective patterns of the metal electrodes or the like. This leads to a serious problem particularly when small patterns are formed over a large area.
A method for forming a metal film to pattern metal electrodes by photolithography techniques is possible in order to solve the above-mentioned problem.
However, this method raises another problem as follows: the organic material may be damaged by a solvent of a resist solution, a developer and an etchant, or by plasma in the case of a dry etching method, whereby characteristics of the light-emitting elements (light-emitting portions) may be degraded.
Moreover, a method for producing an electroluminescence display panel by using a technique of obliquely supplying an upper electrode material onto a substrate having a plurality of stripe-shaped insulation films is described in Japanese Laid-open Publication No. 5-2058859. In this method, however, vapor of the metal electrode material may be undesirably directed to the sides of the insulation films, thereby hindering desirable patterning.